Melt-spun Y1.7Er0.3Fe17 ribbons were prepared at the wheel speed of 20 m/s. The crystal structure, the magnetic entropy change and three-dimensional atomic mapping of the ribbons were investigated. The results indicate that the melt-spun Y1.7Er0.3Fe17 ribbons crystallize in the hexagonal Th2Zn17 structure, and the lattice parameters of main phase Y2Fe17 in the melt-spun Y1.7Er0.3Fe17 ribbons decrease compared with the standard PDF card (48-1454). The Curie temperature of melt-spun Y1.7Er0.3Fe17 ribbons is about 308 K, which is close to room temperature, and the maximum magnetic entropy change for a field change of 0-1.5 T is 2.10 J·kg-1·K-1. Three elements (Y, Er and Fe) uniformly distributed in the three-dimensional space except in the grain boundary with lower Fe content.